(C++) - 백준(BOJ) 1940번 : 주몽 답

#include <iostream>
#include <vector>
using namespace std;
int main() {
    int n, m, cnt = 0;
    cin >> n >> m;
    vector <int> armor(n);
    for (int i = 0; i < n; i++)
        cin >> armor[i];
    for (int i = 0; i < n - 1; i++)
    {
        for (int j = i + 1; j < n; j++)
        {
            if (armor[i] + armor[j] == m)
                cnt++;
        }
    }
    cout << cnt <<'\n';
}